Unclear error if a cycle dependency between namespaces #444

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2022-12-16T17:01:29+09:00

davidyuk commented

2022-12-16 17:01:29 +09:00

(Migrated from gitlab.com)

Reproduction

├── Includes.aes
└── lib
    ├── Library.aes
    └── Sublibrary.aes

Includes.aes

include "./lib/Library.aes"

contract Includes =
    entrypoint test(x: int): int = Library.sum(x, 4)

Library.aes

include "./lib/Sublibrary.aes"

namespace Library =
  type number = int
  function sum(x: int, y: int): int = Sublibrary.sum(x, y)

Sublibrary.aes

include "./lib/Library.aes"

namespace Sublibrary =
  function sum(x: int, y: int): int = x + y
  function return42(): Library.number = 42

CLI prints an unclear error

$ aesophia_cli ./Includes.aes
Type error in 'lib/Sublibrary.aes' at line 5, col 24:
Unbound type Library.number.

Type error in 'lib/Sublibrary.aes' at line 5, col 41:
Cannot unify `int` and `Library.number`
when checking the type of the expression `42 : int` against the expected type `Library.number`
$ aesophia_cli --version     
Sophia compiler version 7.0.1

it works if I include number from another namespace (without cycle deps). Sophia should disallow cycle dependencies explicitly or the above reproduction should work.

## Reproduction ``` ├── Includes.aes └── lib ├── Library.aes └── Sublibrary.aes ``` Includes.aes ``` include "./lib/Library.aes" contract Includes = entrypoint test(x: int): int = Library.sum(x, 4) ``` Library.aes ``` include "./lib/Sublibrary.aes" namespace Library = type number = int function sum(x: int, y: int): int = Sublibrary.sum(x, y) ``` Sublibrary.aes ``` include "./lib/Library.aes" namespace Sublibrary = function sum(x: int, y: int): int = x + y function return42(): Library.number = 42 ``` CLI prints an unclear error ```bash $ aesophia_cli ./Includes.aes Type error in 'lib/Sublibrary.aes' at line 5, col 24: Unbound type Library.number. Type error in 'lib/Sublibrary.aes' at line 5, col 41: Cannot unify `int` and `Library.number` when checking the type of the expression `42 : int` against the expected type `Library.number` $ aesophia_cli --version Sophia compiler version 7.0.1 ``` it works if I include `number` from another namespace (without cycle deps). Sophia should disallow cycle dependencies explicitly or the above reproduction should work.

ghallak commented

2023-03-22 19:47:36 +09:00

(Migrated from gitlab.com)

First, this has nothing to do with includes. You can put the namespaces in the same file and it will still not work.

The error is produced because a namespace can only recognize what was written before it, so if you want to have a base namespace and a dependent namespace, you should have them in order.

namespace Base =
    ...

namespace Dependent =
    ...

Is there a specific situation where you need 2 namespaces to depend on each other, and you're not better off refactoring the code?

I would say that it's better to keep it this way in order to prevent messy designs, and the error messages are clear enough once you know that a namespace can only recognize what's written before it.

@radrow Do you have any opinion on this?

First, this has nothing to do with includes. You can put the namespaces in the same file and it will still not work. The error is produced because a namespace can only recognize what was written before it, so if you want to have a base namespace and a dependent namespace, you should have them in order. ``` namespace Base = ... namespace Dependent = ... ``` Is there a specific situation where you need 2 namespaces to depend on each other, and you're not better off refactoring the code? I would say that it's better to keep it this way in order to prevent messy designs, and the error messages are clear enough once you know that a namespace can only recognize what's written before it. @radrow Do you have any opinion on this?

zxq9 commented

2023-03-22 20:10:01 +09:00

(Migrated from gitlab.com)

Created by: radrow

I think it would be much more user friendly if we explicitly point out that dependency cycles are not supported. For example functions within one namespace do support mutual recursion, so I can imagine this being confusing.

*Created by: radrow* I think it would be much more user friendly if we explicitly point out that dependency cycles are not supported. For example functions within one namespace do support mutual recursion, so I can imagine this being confusing.

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Reference: QPQ-AG/sophia#444